The research program will use the latest technology for assessing neural activity, that of intrinsic optical imaging, together with single neuron and surface recording. The research plan will examine how rostral brain areas affect respiratory control during sleep in the development animal so that mechanisms of respiratory failure can be understood in victims of SIDS. State influences modify descending input from rostral brain regions to specific brainstem respiratory areas, and place the developing organism at risk for obstructive sleep apnea by differentially enhancing diaphragmatic over upper airway action.; the extent of rostral influences vary with development. Among rostral brain areas, the anterior hypothalamus/preoptic area exters substantial breathing influence by mediating thermal influences to respiratory sites. Sleep states can diminish or abolish descending thermal drive, thus blunting a large component of arousal-mediated upper airway muscle activation. We will examine the development of anterior hypothalamic neural activity to respiratory patterns at 3 ages in the kitten by 1) examining "spontaneous" neural activity in the preoptic/anterior hypothalamus and in the motor column of branchial arch muscles during sleet and waking, and relating this activity to upper airway and diaphragmatic pattering, and 2) evoking activity in preoptic/anterior hypothalamic regions by environmental and local warming of the rostral brain site, and examining the resultant influences on local and brain stem neural interactions and overall activity will be assessed with intrinsic optical imaging procedures. Respiratory dependencies will be determined by cross- correlating cell discharge with patterning of the diaphragm and an upper airway dilator (the posterior cricoarytenoid); regression procedures will determine relationships with aspects of the respiratory cycle and with blood pressure. Evoked activity will include warming of the preoptic region to manipulate temperature "drive" to respiration during each sleep-waking state, graded hypoxic and hypercapnic ventilatory challenges, and pharmacologic pressor stimulation.